Production of butadiene monochlorohydrin



Patented Apr. 15, 1952 PRODUCTION OF BUTADIEN E MONOCHLOROHYDRIN Warren L. Towle, Akron, Ohio, assignor, by mesne assignments, to Columbia-Southern Chemical Corporation, Pittsburgh, -Pa., a corporation of Delaware No Drawing. Application April-2'6', 1946, Serial No. 665,317

9 Claims.

The present invention relates to the production of chlorohydrins and more particularlyto the preparationrof amono'chlorohydrin of a diolefin,.butadiene-1;3.

Processes for the preparation of chlorohydrins from unsaturated organic compounds are well known. Such processes are, however, subject to various operating difficulties. For example,. hypochlorination. of olefins is most logically effected by the-direct reaction of hypochlorous acid therewith,.but:solutions.ofhypochlorous acid are relatively unstable and frequently contain decomposition products which induce objectionable side reactions formingr wasteful by-products. In

endeavor toimprove both quantity andquality" oithe chlorohydrinsiproduced, operators have preferred to generate hypochlorous acid situ The primary object of my invention is to provide a method of procedure whereby the hypochlorination of a dioelfin, butadiene-1,3 can be controlled to yield a monochlorohydrin rather than a dichlorohydrin.

Other objects and advantages of the invention will be evident from the following description of certain preferred embodiments thereof.

The preparation of butadiene monochlorohydrin, as contemplated by my invention is comparatively simple. Butadiene is dissolved in a cooled aqueous solution of butadiene monochlorohydrin, a solution of hypochlorous acid is combined therewith under conditions of vigorous agitation, and the mixed solutions are maintained below a temperature of C. while the reaction proceeds. Thereafter the reaction mixture is apportioned, part being recycled to form the solvent medium for additional butadiene While the remainder undergoes treatment for the recovery of butadiene monochlorohydrin.

Despite the simple mechanics of my process, however, certain conditions must be established and observed throughout to insure optimum yields. Inasmuch as high ratios of butadiene concentration to butadiene monochlorohydrin' concentration favor limitationof the hypochlorous acid addition to the saturation of only one of thetwo unsaturated linkages and since, from the standpoint of "product recovery, it is desirable to produce as concentrated a solution of butadiene monochlorohydrin as is consistent with good yield,suificient'butadiene-is introduced into the butadiene monochlorohydrin solution to result in substantial saturation thereof. Under ordinary conditions of pressure and at reduced temperatures butadiene is sufficiently soluble in water that it is possible to obtain a solution wherein the molecular ratioof butadiene to butadiene monochlorohydrin is appreciable. This ratio could be made' even greater by operating under increased pressures. No attempthas been made to'ascertain the upper limit of this molecular ratio'of butadiene to butadiene monochlorohydrin. I have determined, however, that this ratio should be in excess of 0.1 at all times and preferably this ratio is maintained in excess of 0.2.

A highly satisfactory method of obtaining the butadiene-butadiene monochlorohydrin reaction liquor is to pass the cooled monochlorohydrin solution downwardly through a packed absorption tower against a current of butadiene. As the butadiene-butadiene monochlorohydrin solution leaves the bottom of the tower, it is mixed with a solution of hypochlorous acid of low concentration under conditions of vigorous agitation and is pumped through a heat-exchanger cooled with brine to maintain the reaction mixture below 15 C.

Inasmuch as the concentration of hypochlorous acid directly determines the amount of butadiene monochlorohydrin in the final product, it also determines the concentration of butadiene monochlorohydrin in the recycled reaction liquor, which in turn influences the solubility .of butadiene in the recycled reaction liquor. Thus a low concentration of hypochlorous-acid in the feed solution aids in maintaining the high ratio of butadiene to butadiene monochlorohydrin previously indicated to be desirable. The hypochlorous acid concentration must be below 50 gms. per liter of. feed solution and it is preferred that the concentration fall within the range of from 5 to 15 gms; of hypochlorous acid per liter of feed. solution; This low concentration of hypochlorous acid in the feed solution must also be correlated with the butadiene content of the butadiene monochlorohydrin recycled reaction liquor. By maintaining a or'greater excess of butadiene in the butadiene monochlorohydrm reaction liquor leaving the absorption tower at an approximate concentration of 1.5 grams per liter for admixture with the hypochlorous acid feed solution of a concentration of about 10 4 ulated data indicates clearly the effect of the hypochlorous acid concentration upon the yield; that is, the yield increases as the hypochlorous acid concentration decreases. It is believed that grams per liter, it has been possible to attain this effect is due largely to the change in the maximum yields. Excesses of butadiene considmolecular ratio of the butadiene to the butadiene erably above 150% have little apparent effect on monochlorohydrin. The concentrations of butathe yield. Amounts of butadiene below this figdiene and hypochlorous acid in the reaction ure, however, materially reduce the yield. Exliquor are substantially the same in the first six pressed differently, I have determined that the experiments, but the concentration of butadimolecular ratio of dissolved butadiene in the reene monochlorohydrin is roughly proportional cycled reaction liquor leaving the absorption to the hypochlorous acid concentration in the tower to the hypochlorous acid in the feed solufeed liquor. This change in concentration ratios tion should be at least 1.3 and preferably should naturally affects the amount of butadiene monobe in excess of 2.5. This balance is readily eschlorohydrin which can react with the hypotablished and maintained in the operation of a chlorous acid to form butadiene dichlorohydrin. continuous process. In the final five experiments the hypochlorous It is readily apparent that the intermixing of acid feed concentration is nearly constant while the butadiene-monochlorohydrin reaction liquor the amount of butadiene in the reaction liquor is and the hypochlorous acid feed liquor should be Varied- These fi eXDerimentS us rate the 'as rapid as possible to avoid existence of localized effect of an excess of butadiene upon t yields relatively high concentrations of hypochlorous of butadiene monochlorohydrin. acid. Where sufiicient hypochlorous acid is In the prece i examples, the yp orous present to exhaust the butadiene available for acid employed was substantially pure. Decomreaction therewith, the monochlorohydrin will position of hypochlorous acid yields chloric acid undergo reaction with the remainder of the and Chlorine The presence rine in the hypochlorous acid, resulting in undesired formahypeehloreus acid e l quor results in butation of butadiene dichlorohydrin, The interdiene dichloride formation together with some mixing of reactant s l ti n may be accomchlorine addition to the butadiene monochloroplished in many ways but the most convenient hydrih, hus reduci the Yield of buta iene is a direct feed of the hypochlorous acid solution monochlorohydrin. Manifestly therefore, hypointo the casing of a centrifugal pump moving the chlorous acid substantially free of chlorine should monochlorohydrin reaction liquor from the abbe mp y in my pr c ss- For pt mum su ts. sorptjon t we t the heat exchanger, In this it is preferred that the hypochlorous acid conmanner the mixing takes place with the greatest 3.3 ain le h n -1 q iv of chloride ion D possible turb len equivalent of hypochlorous acid. Hypochlorous The reaction mixture circulates through a heat acid solutions may be freed from contaminating exchanger in order that the temperature thereof chlorine, prese as the result f decomposition, is maintained below about 15 c. At temperaby s mpl l win with air, and us pr p .tures above 15 C., an undesirable side reaction f u in the yp erination reaction. reduces the yield of monochlorohydrin. It Hypochlorination of butadiene under the conshould also be noted that by holding the temditions set forth hereinbefore enables production perature of the reaction liquor below 15 C. the of high yields of butadiene monochlorohydrin. absorption of butadiene in the recycled portion The specified conditions, of no importance in the is facilitated. Of course, the temperature of the hypochlorination of mono-unsaturated olefins or reaction liquor may be reduced considerably bethe formation of dichlorohydrins, are essential low 15 C. with a corresponding increase in the to the production of butadiene monochlorohydrin yield of monochlorohydrin. Best yields are 0bin optimum yields. tained when the temperature is held in the range Wh t 1 1 m; i of from 0 t0 1. A process of manufacturing butadiene The results of a n m r o e periments are monochlorohydrin which comprises mixing hypre ented n t e o ow ng a pochlorous acid solution containing less than 50 Table I Example No. l 2 3 4 5 0 7 8 9 10 ll Concentration of H001 in feed (guns/liter) 40.5 30.2 28.4 21.5 10.8 2.9 0.95 10.05 10.0 0.95 9.05 HOG} feed rate (mls./ min.) 250 250 250 250 250 250 1, 50 1, 350 1,250 1,050 800 H001 feed rate (gms./

hr.) 008 450 420 323 102 4a 747 815 750 000 477 Reaction temp. o. 1 1 1 1 1 1 2.0 2 1.5 1 1 H001 and Ch in reaction liquor 1 H001 0.00 0.13 0.01 0. 01 0.01 0.2 Butadiene in reaction liqnor (g./1) 2.2 1.0 0a 1.2 1.0 0.0 1.9 0.8 1.0 1.5 1.5 Butadiene solution, recirculation rate (gals/min). 6.0 6.0 6.0 6.0 6.0 0.0 3.0 6.1 4.0 6.1 6.0 Total unsaturate in reaction liquor as g./l Monochlorohydrin 57.0 40.7 45 35.2 19.9 5.4 15.1 10.4 10.5 17.0 17.5 Per cent yield of unsaturates, basis H001 09.4 74.5 78.2 80.7 90.9 92.5 s1 s7 89 In the experiments, above tabulated, certain of grams of HOCl per liter of hypochlorous acid the conditions hereinbefore specified as affecting solution, under conditions of vigorous agitation, the operation of the process have been standardwith butadiene dissolved in an aqueous solution ized, the better to illustrate the effect of variaof butadiene monochlorghydrin at a, tempera,-

ture below 15 0., the molecular ratio of butations of the remaining conditions. The tabmoleculafratio of butadiene to butadiene monochlorohydrin in solution being maintained in excess of 0.1 and the molecular ratio of butadiene added to the hypochlorous acid being maintained in excess of 1.3.

3. A process of manufacturing butadiene Q /mQnochlOrOHy drin which comprises mixing hypochlorous acid solution which contains less than 50 grams of HOCl per liter of hypochlorous acid solution, said solution containing less than 0.1 equivalent of chloride ion per equivalent of hypochlorous acid, under conditions of vigorous agitation with butadiene dissolved in an aqueous solution of butadiene monochlorohydrin at a temperature below about 5 C., the molecular ratio of butadiene to butadiene monochlorohydrin added being maintained in excess of 0.2 and the molecular ratio of butadiene in solution to the hypochlorous acid being maintained in excess of 2.5.

4. A process of manufacturing butadiene monochlorohydrin which comprises mixing an aqueous solution of hypochlorous acid of a concentration of from 5 to 15 grams per liter and containing less than 0.1 equivalent of chloride ion per equivalent of hypochlorous acid under conditions of vigorous agitation with butadiene dissolved in an aqueous solution of butadiene monochlorohydrin at a temperature below about 5 C., the molecular ratio of butadiene to butadiene monochlorohydrin added being maintained in excess of 0.2 and the molecular ratio of butadiene in solution to the hypochlorous acid being maintained in excess of 2.5.

5. A process of manufacturing butadiene monochlorohydrin which comprises circulating an aqueous solution of butadiene monochlorohy drin through a continuous system, dissolving suflicient butadiene in the circulating monochlorohydrin solution to attain a molecular ratio of butadiene to butadiene monochlorohydrin in excess of 0.2, mixing an aqueous solution of hypochlorous acid of a concentration of from 5 to 15 grams per liter and containing less than 0.1 equivalent of chloride ion per equivalent of hypochlorous acid with the butadiene-butadiene monochlorohydrin solution, regulating the input of hypochlorous acid to maintain a molecular ratio of butadiene added to hypochlorous acid in excess of 2.5, maintaining the temperature of the mixed solutions below about 5 C. during the course of the reaction between the hypochlorous acid and butadiene, separating a portion of the reaction mixture to enable recovery therefrom of butadiene monochlorohydrin, and recycling the remainder of the reaction mixture.

6. A process of preparing butadiene monochlorohydrin which comprises dissolving sufficient butadiene in a butadiene monochlorohydrin aqueous solution'to establish a molecular ratio of butadiene to butadiene monochlorohydrin in excess of 0.2, vigorously mixing an aqueous solution of hypochlorous acid containing 5 to 15 grams per liter of hypochlorous acid with the butadiene-butadiene monochlorohydrin solution, regulating the input of hypochlorous acid to maintain a molecular ratio of butadiene added to hypochlorous acid in excess of 2.5, maintaining the temperature of the mixed solutions at below about 5 C. during the course of the reaction between the hypochlorous acid and the butadiene, separating a portion of the reaction mixture to enable recovery therefrom of butadiene monochlorohydrin, and recycling the remainder of the reaction mixture.

7. A method of preparing butadiene monochlorohydrin which comprises successively dissolving butadiene in an aqueous solution of butadiene monochlorohydrin, vigorously mixing aqueous hypochlorous acid containing up to 50 grams per liter of hypochlorous acid with the butadiene solution while maintaining the temperature below 15 0., the molecular proportion of butadiene to hypochlorous acid being at least 1.3, adding further butadiene to the resulting mixture after the hypochlorous acid has been consumed, and reacting the resulting product with further hypochlorous acid.

8. A process of preparing butadiene monochlorohydrin which comprises dissolving butadiene in butadiene monochlorohydrin and water to form a solution thereof in which the molecular ratio of butadiene to butadiene monochlorohydrin in solution is in excess of 0.1, mixing said solution with an aqueous solution of hypochlorous-acid which contains less than 50 grams of H001 per liter of hypochlorous acid solution, maintaining the temperature of mixing below 15 C. while proportioning the amounts of.said solutions to insure maintenance of a molecular ratio of butadiene in solution to hypochlorous acid in excess of 1.3, Withdrawing at least a portion of the butadiene monochlorohydrin thus produced from the reaction mixture, dissolving further butadiene therein and recycling said solution to the reaction mixture.

9. The process of claim 8 wherein the temperature of mixing is maintained below 15 C. and the concentration of the hypochlorous acid solution is maintained below 15 grams per liter.

WARREN L. TO-WLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,456,916 Curme et a1 May 29, 1923 1,456,959 Young May 29, 1923 1,465,595 Brooks Aug. 21, 1923 

1. A PROCESS OF MANUFACTURING BUTADIENE MONOCHLOROHYDRIN WHICH COMPRISES MIXING HYPOCHLOROUS ACID SOLUTION CONTAINING LESS THAN 50 GRAMS OF HOCL PER LITER OF HYPOCHLOROUS ACID SOLUTION, UNDER CONDITIONS OF VIGOROUS AGITATION, WITH BUTADIENE DISSOLVED IN AN AQUEOUS SOLUTION OF BUTADIENE MONOCHLOROHYDRIN AT A TEMPERATURE BELOW 15* C., THE MOLECULAR RATIO OF BUTADIENE TO BUTADIENE MONOCHLOROHYDRIN ADDED BEING MAINTAINED IN EXCESS OF 0.1 AND THE MOLECULAR RATIO OF BUTADIENE IN SOLUTION TO THE HYDOCHLOROUS ACID BEING MAINTAINED IN EXCESS OF 1.3. 